We're aware of this issue and a fix is coming soon. Speaking to the "Why is this so hard?" discussion, the simple fact is that we haven't reskinned a weapon's projectiles before except for bows which are their own specific animal. So there's some new infrastructure that has to be built behind the scenes to allow this. The bug where Stahlta fails to explode on alt fire is a direct result of fixing the issue where the Unreal skins would cause a Kuva weapon to behave as if it was the non-Kuva